A US Drug Enforcement Administration agent died from stab wounds in an apparent robbery during a taxi ride from an exclusive part of Bogota yesterday, and Colombia's president said no effort would be spared to find those responsible.

Special Agent James "Terry" Watson was killed after hailing a taxi outside a restaurant in the Colombian capital's Parque de la 93 area, Colonel Camilo Cabana of the Bogota police told reporters today.

Watson, a 13-year veteran of the DEA, escaped the vehicle after being stabbed and was taken to a local hospital where he died, Cabana said.

Santos called on the defense ministry to do everything possible to find the killers.

"Events like last night's when a DEA agent was killed in a taxi, erases in one swipe all the effort we have made to reduce murder," Santos said during a ceremony in Bogota where he was promoting police officers.

"No effort should be spared to get those responsible for this murder."

Crime in Colombia has fallen sharply over the last decade in step with a US-backed offensive against drug gangs, paramilitaries and Marxist rebels. The murder rate has dropped about 36 percent since 2003, the year after Santos' predecessor, Alvaro Uribe, took office on a pledge to improve security.

But poverty remains rife in Bogota and crime is one of the top concerns for its residents.

Police said Watson's death did not appear connected to his work and that the agent likely had been taken on what is known as a "millionaire ride," in which passengers are taken to a spot where a driver's accomplices are waiting. The victims are then driven to cash machines where they are forced to withdraw money.

The US ambassador to Colombia, P. Michael McKinley, said Watson left the restaurant after watching a basketball game with friends.

"What we have established is that it was a classic criminal robbery that ended in tragedy," McKinley said on local radio.

Watson was assigned to the DEA's office in the coastal city of Cartagena but on temporary duty in Bogota, according to a statement from the DEA. He was deployed three times to Afghanistan on anti-narcotics missions and had served in the US Army.

"We are all saddened by this devastating loss of a member of the DEA family," DEA Administrator Michele Leonhart said in the statement. "Terry was a brave and talented DEA special agent who served our agency for 13 years. These are the worst days for anyone in law enforcement and we grieve Terry's loss."

US officials in Bogota and police are watching video recordings of the area where the agent was picked up. A reward of 50 million pesos (US$25,800) has been offered for information, said General Jose Roberto Leon, the national police chief.